Method of preparing luminescent tubes



Patented Mar. 12, 1929.

PAUL FRANQOIS JOSEPH LEBRUN, OF PARIS, FRANCE.

METHOD OF PREPARING LUMINESCENT TUBES.

Ho Drawing.

This invention relates to a method of preparing luminescent tubes, and the objects of the invention are to eliminate as far as possible occluded gases and impurities from the interior surface of the tube, prior to the permanent filling thereof with the luminescent gas, and it consists essentially in the treatment of the tube with a conducting vapour such as ethyl alcohol or methyl alcohol from which a high tension current is passed in the manner hereinafter more fully set forth and described.

In manufacturing luminescent tube, according to the present invention, the electrodes themselves are preferably first given a scavenging treatment of a heated gas before insertion in the tube. This may be done by heating electrodes in a suitable container filled with a scavenging gas, such as nitrogen or a mixture of nitrogen and hydrogen, to a temperature of from 700 to 800 G., for a period of from 15 to 20 minutes. The electrodes are then placed in a bulb, which is to be welded to the luminescent tube, but before welding takes place a few drops of a liquid, such as ethyl alcohol or methyl alcohol designed to produce a conducting vapour, are introduced into the bull. The bulb is then sealed by Welding to the tube, and a preliminary incomplete vacuum is made, by exhausting with a suitable vacuum pump, thereby producing in the tube, a raritied mixture of gaseous ethyl alcohol or methyl alcohol and air. This incomplete vacuum may be in the neighborhood of .007.005 mm. of mercury.

A high tension current of the order of 10.000 volts is then passed through this gaseous mixture for a short period of time say from 5 to (5 minutes. The vacuum pump is then connected to the tube, and the vacuum treated as far as possible, say to .0001 mm.

Application filed August 26, 1927. Serial No. 215,751.

of mercury. The tube is then filled with the luminescent gas, such as neon, which is to constitute the final filling.

As many changes could be made in the above construction,

widely different embodiments of my invention, within the scope of the claims, con

structed without departing or scope thereof, it is intended that all matter contained in the accompanying specifi "L tion shall be interpreted as not in a limiting sense.

What I claim as my invention is:

1. In the man tubes, the herein described method of treatmg a tube, prior to filling thereof with luminescent gas,

final filling, which comprises forming a rarified mixture of holic vapour in the air and a conducting alcohigh tension current therethrough.

2. The method as claimed in claim 1, in

which the vapour is formed from ethylalcohol.

8. The method as which the high tension current is of the order of 10.000 volts.

4. A luminescent tub o. The method as claimed in claim 1, in

which the vapour is formed by adding a few drops of ethyl-alcohol to cleaning the. electrodes the bulbs, and prior to connecting the bulbs to the tube.

In witness whereof I have hereunto set my hand.

PAUL FRANCOIS JOSEPH LEBRUN.

and many apparently from the spirit illustrative and ufacture of luminescent which is to constitute its tube, and passing the claimed in claim 1, in

e prepared according 

